1. Field of the Invention
The present invention relates to high barrier multilayer films incorporating a biodegradable polymer layer. More particularly, the invention pertains to biodegradable insulation facing materials incorporating a biodegradable polymer layer.
2. Description of the Related Art
A wide variety of polymers and films formed from such polymers are known. Important physical characteristics of such films include its barrier properties, including barriers to gas, aroma, and/or vapor such as water vapor, as well as its physical characteristics, such as toughness, wear and weathering resistances, and light-transmittance. It is also well known to manufacture polymeric film articles for use in a wide array of applications, such as packaging applications. Many such articles are made of multiple layers of different plastics in order to achieve various desired physical and chemical properties.
Conventionally, synthetic polymers such as polyethylene (“PE”), polypropylene (“PP”) and polyethylene terephthalate (“PET”), etc. are widely used as materials for manufacturing multilayer packaging materials for containing various objects. After use, disposal of the used packaging materials frequently leads to their being sent to a facility where they are decomposed by incineration at high temperatures. However, the incineration of such synthetic polymers typically generates substances that contaminate the air and pollute the environment. These materials are also high in heat buildup when burned and there is a possibility of damaging the incinerator during burning treatment. Other materials, such as polyvinyl chlorides, cannot be burned because they have self-extinguishing properties. One common means to ameliorate this problem is by recycling and reusing the materials, but recycling can be very expensive and often is not economically feasible. Such synthetic polymer materials that are disposed without being incinerated or recycled typically are buried in landfills and generally do not decompose, permanently taking up space as waste.
In view of these issues, biodegradable polymers and products formed therefrom are becoming increasingly important. Biodegradable polymers are typically produced from annually renewable resources, such as corn or sugarcane, and may be naturally produced, modified naturally produced or synthetically produced. One particularly desirable family of biodegradable polymers is polylactic acids (“PLAs”), also referred to as polylactides. PLAs are synthetic aliphatic polyesters derived from renewable resources. Bacterial fermentation of corn starch or sugarcane produces lactic acid which is then condensation polymerized to form PLA.
Polylactic acids are desirable because their heat buildup during burning is less than half that of polyethylene and they are naturally decomposed in soil or water. However, other less desirable properties limit the broad market entry of PLAs and other biodegradable polymers in plastics industries compared to a conventional polymer such as polyethylene or polystyrene. For example, polylactides and other biodegradable polymers such as polyhydroxyalkanoates (“PHAs”) have poor gas and moisture barrier properties and are not well suited for use as packaging materials or in other applications where a high barrier to gas and/or moisture is desired. Films produced from such annually renewable materials tend to be noisy when deformed and many compositions that have excellent degradability have only limited processability. Additionally, films produced from annually renewable materials have a tendency to easily tear and crack, in addition to having poor gas and moisture barrier properties.
Accordingly, there is a need for environmentally friendly multilayer film structures having good processability and a high barrier to gas and moisture transmission that are useful as insulation facings. The present application provides a solution to this need.